Propellant powder charge for barrel weapon

ABSTRACT

The present invention relates to a method for producing propellant powder charges intended for heavy barrel weapons, such as canons and howitzers, and with a high degree of filling and a high energy content, and also to propellant powder charges produced in accordance with this method. The charges according to the invention are distinguished by the fact that 70 to 95% of their weight consists of a more coarsely grained powder and 30 to 5% consists of a granular powder with a smaller grain size. These two powders have the same of different chemical composition, and one or more of them can be surface-inhibited.

The present invention relates to a propellant powder charge with highprogressivity and an extremely high degree of filling or loadingdensity, intended primarily for large-bore barrel weapons.

In what today is the most common way of producing progressive propellantpowder charges intended for large-bore barrel weapons, use is madeprimarily of what is known as granular holed powder, i.e. powderproduced by extrusion in a matrix, cut up into short rods or cylinders,with one, seven, nineteen or thirty seven longitudinal priming channels.Because of its geometric configurations throughout its burn time, exceptduring the absolutely final stage, multiple-hole powder of this kind hasgood progressive burn properties by virtue of the fact that as they areprimed they burn from all the surfaces available for priming, i.e. fromthe outsides of the grains and from the insides of the priming channels,and, from these surfaces thereby primed, the powder will burn towardsother primed surfaces during a successive increase of the burn area, andthe gas release thereby also increases.

In order to launch a defined missile from a defined barrel weapon with apredetermined Vo, i.e. with a defined launch velocity immediatelyoutside the barrel mouth, the propellant powder has to be able todeliver a certain additional amount of energy. This additional energy,which can be calculated theoretically with great accuracy, must bedelivered during the missile's travel through the barrel. This in turnmeans that the propellant powder must have time to burn out during thetime the missile is on its way through the barrel. The period of timewhich the propellant powder should then have to burn out and which isthus the same as the time the missile has to pass through the barrel canbe called the “burn time”.

If at the same time the length which a powder with the chemicalcomposition in question is able to burn is also called the “burn time”,this means that the distance between two adjacent priming channels in amultiple-hole powder which has the desired burn time will correspond totwice the burn length which the burn time in question permits. Thedistance from respective priming channels to the outer side of thegranular powder in which the priming channel is formed must be the samesize, provided that the powder grains have not been surface-treated witha burn inhibitor, which is sometimes done in order to increase thepowder's progressivity. In summary, it is readily possible to producemultiple-hole powders with different progressivity using differentnumbers of priming channels, the individual powder grains being given agreater inherent volume depending on the number of priming channels. Theprogressivity of the powder can then in turn be accentuated by surfacetreatment with a suitable substance which is more difficult to ignite,but burnable.

The main trends in modern-day arterillery technology are to attempt byall possible means to increase the artillery's range of fire and itsfiring speed. In view of the refined methods which have been developedin recent years, and which allow an opponent to determine quickly andwith very great accuracy from where he has been shot at, it is thus alsonecessary to rapidly change the site of firing each time the barrel hasbeen opened.

Increased firing speed is mainly achieved by the introduction ofmechanized loading systems, and these will not be discussed in anydetail here, nor will the tactical need for rapidly changing the firingpositions. By contrast, it has been found that older artillery piecestoo which are in good condition can be given much longer ranges of fireby means of newly developed and high-energy powder charges and possiblyalso newly developed shells. However, a problem in this context, whichis often more serious than the strength limits of barrel and mechanism,is that the space in the rear part of the barrel, i.e. its chamberposition, which is available for the actual propellant charge is toosmall to accommodate a conventionally configured propellant powdercharge with sufficient energy content for this desired increase in therange of fire.

The present invention now relates to a method using holed or unholedgranular powder to produce progressive propellant powder charges with ahigher degree of filling or loading density and thus also loadingweights than has previously been possible. The invention also includespropellant powder charges produced in accordance with said method.

The starting point for the method according to the invention is that,between the grains of a granular powder introduced into a containerwithout any kind of organized order, there will automatically be a verylarge number of greater or lesser empty volumes which are many but smallin the case of a finely grained powder and which are fewer but alsolarger in a coarser-grained powder.

Our solution to the problem now is so simple that it is astonishing thatit has not been done earlier. According to the underlying principle ofthe present invention, we in fact mix two or more different sorts ofgranular powder in proportions adapted for the particular purpose, wherethe more finely grained powder is able to fill the otherwise empty spacebetween the larger powder grains. By suitable choice of powder types andsuitable proportions between them, it is thus possible to producecharges which have loading densities lying very near to or higher thanthose one would have obtained if the powder grains had been rammed inmanually for the best degree of packing, and the latter method isentirely excluded for practical use. The only additional measure whichmay be required in connection with the present invention is that thecharges are vibrated during powder filling, which is also preferablydone simultaneously with the two powder types. One or more of the powdertypes used can additionally be surface-treated or surface-inhibited inorder to further control the progressivity.

The present invention thus makes it possible to produce propellantpowder charges with a high loading density and exactly the high energycontent which is required for the case in question. A propellant powdercharge produced according to the invention can thus contain 70-95% byweight of a coarsely grained multiple-hole powder, for example a 19-holeor 37-hole powder, and 30-5% by weight of a smaller multiple-holepowder, for example a 1-hole powder or 7-holed powder, and, in view ofthe desired final result, the powders can each have the same ordifferent chemcial composition and be surface-inhibited (surface-treatedwith suitable burn inhibitors) or not surface-inhibited. The percentagesshown above apply to the outer limits characterizing the invention,whereas, when in practice calculating the charges of the typecharacterizing the invention, they will in most cases be in the range of75-85% by weight for the coarser multiple-hole powder and 25-15% byweight for the multiple-hole and more finely grained powder or powders.

The nearest prior art we are aware of is the charge which is describedin U.S. Pat. No. 4,519,855 which describes a propellant powder chargefor ballistic ammunition comprising a first powder component consistingof large balls or spheres easily fragmentable into small grains of afirst powder component surrounded by a second powder component in theform of a conventionally granular powder which fills the space betweenthe large spheres of powder. Here too the aim has been to produce apowder charge with the highest possible degree of filling taking intoconsideration the powder types used, but the progressivity of thecharges obtained by this method will be based primarily on the largespheres of powder bursting apart during combustion of the powder andthereafter burning like conventionally granular powder, whereas theprogressivity for our specific charge is based entirely on the originalgeometrical shape of the powder grains used.

The present invention thus relates to a method in which granular powderis used to produce propellant powder charges with high degree of fillingor loading density and a high energy content per charge. The inventionalso covers the charge produced by this method. The invention also makesit possible to produce charges with precisely controlled progressivecharacteristics by virtue of the fact that it can be built up fromdifferent quantities of different powders which have radically differentprogressive characteristics.

The invention is thus based entirely on combining two or more types ofgranular powder having such geometric external shapes and grain sizesthat the powder with the smaller grain size will in the best possibleway fill the empty space between the larger grains.

The invention has in all its features been defined in the attachedpatent claims and it can be illustrated by the following example.

EXAMPLE

From a nitrocellulose powder of standard quality which we have used formany years for producing artillery powder, we produced on the one hand a19-hole powder with grain size of 17×17 mm and a 1-hole powder with agrain size of 5×5 mm. Of these powders, we mixed 2.3 kg of the 19-holepowder with 0.5 kg of the 1-hole powder and thus obtained a charge withan energy content corresponding to 122% of the energy content in astandard charge which we had previously produced and which was made onlyfrom 19-hole powder. Both the charge types are held in the same volume.The invention thus makes it possible to achieve considerable advantagesby very small means.

1-7. (Cancelled).
 8. A method for producing progressive propellant powder charges suitable for use in barrel weapons having a high degree of filling or loading density and thus also a high energy content at which the charge is produced, the method comprising: mixing at least two types of granular powder of different grain size, of which at least one of the at least two powder types with a largest grain size and a larger number of internal priming channels has a progressive burn characteristic, wherein, as subsidiary components of an actual charge, granular powders are chosen having size, geometric shape, and quantities adapted to give a smallest possible empty spaces between the powder grains.
 9. The method of claim 1, wherein a starting material chosen for the charge comprises at least two types of powder whose mutual progressivity has been optimized for a particular purpose.
 10. The method of claim 1, wherein a starting material chosen for the charge comprises granular powder having a same or different chemical composition, but with different grain size and a different number of internal priming channels.
 11. The method of claim 1, wherein, when choosing a starting material, powder types are chosen of which one or more are surface-inhibited.
 12. The method of claim 1, wherein, of the powder types included in a finished charge, all the types are introduced contemporaneously with each other and, at the same time a casing or cartridge to which the powder is added and in which the charge is to be stored prior to use is subjected to vibrations which improve a degree of packing of the charge.
 13. Propellant powder charge suitable for use in barrel weapons and having a high degree of filling or loading density and with a high energy content, the power charge comprising: at least two different types of granular powder of which at least one type has a progressive burn characteristic and in which one or more of these powders is surface-inhibited, wherein burn characteristics of each of these different powders are adapted to one another while their mutual grain sizes and quantities of each powder included in a charge are adapted to one another such that an empty space remaining between the powder grains is minimized.
 14. The propellant powder charge of claim 13, wherein between 70-95% of a powder charge weight comprises relatively coarsely grained powder, and wherein 30-5% of the weight comprises a relatively more finely grained powder, wherein these two powders have a same or different chemical composition and at least one of the two powders is progressive and one or more of the two powders is surface-inhibited.
 15. The propellant powder charge of claim 14, wherein between 75 to 85% of of a powder charge weight comprises relatively coarsely grained powder.
 16. The propellant powder charge of claim 14, wherein the coarsely grained powder is either 19-hole or 37-hole powder cut into short sections.
 17. The propellant powder charge of claim 14, wherein the finely grained powder is either 1-hole or 7-hole powder. 